Posted on

Air Velocity and Flow Measurement with Pitot Tubes

Pitot Tubes Series 160, 166T, and 160S

Dwyer offers many styles of Pitot tubes. Pitot tubes are commonly used sensors for monitoring air velocity and flow rate in heating, ventilation, and air conditioning. Some examples include the: Stainless Steel Pitot Tube Series 160, Telescoping Stainless Steel Pitot Tube Series 166T, and “S” Type Stainless Steel Pitot Tube Series 160S.

Henri Pitot

Pitot tubes are based on Bernoulli’s equation, which states that an increase in the speed of a fluid occurs simultaneously with an increase in dynamic pressure and a decrease in static pressure. Pitot tubes sense the dynamic pressure of the fluid flow at a particular point and were invented by French Engineer Henri Pitot in the early 18th century. Continue reading “Air Velocity and Flow Measurement with Pitot Tubes”

Posted on

Use of Gold Contact Snap-Action Switches

Push Button Snap-Action Switches

Many Dwyer Instruments, Inc. switch products have standard snap-action switches. Snap-action switches have a mechanical movement that snaps the contacts together and apart to make or break an electrical circuit.

Silver contact snap switches are very versatile and offer high contact ratings commonly up to 10 or 15 amps when used with 120 volts AC. These switches are often used for control circuits with heavier load requirements such as pumps, motors, fans, and incandescent light bulbs.  Continue reading “Use of Gold Contact Snap-Action Switches”

Posted on

RTD Temperature Sensors

Temperature Sensors

Dwyer Instruments, Inc. offers a wide variety of temperature sensors that use RTDs as the sensing element.

RTDs are based on the principal that the electrical resistance of the wire is a function of the temperature, with the resistance increasing as temperature increases. The resistance varies nearly linearly with temperature per the Callendar Van-Dusen equation. The wire used in RTDs as the sensing element is usually constructed of platinum, copper, or nickel.  Platinum is the best material for this element, as it has the widest useful temperature range of these materials. It also has a very repeatable and linear temperature to resistance correlation. Continue reading “RTD Temperature Sensors”

Posted on

U.S. and International Threaded Connection Standards

Threaded Connections

Threaded connections are often referred to as a process connection type. For Dwyer product specifications, this connection type is typically NPT (National Pipe Thread), which is an American standard thread. These connections allow products to be installed directly into piping or with the use of threaded fittings.

For threaded connections there are two common types, (1.) straight or parallel thread and (2.) tapered thread. Continue reading “U.S. and International Threaded Connection Standards”